Conventional shielded electrical connectors are shown in FIGS. 4, 5A and 5B as disclosed in Patent Publication No. 90-108277.
Shielded connector 100 shown in FIG. 4 comprises an insulating housing 101 having an L-shaped cross-sectional profile which includes a connecting section 101a and mounting section 101b, multiple electrical contacts 102 are secured in the connecting section 101a and a metal shield 103 shields contacts 102 and is secured on the connecting section 101a of the housing 101. The metal shield 103 is connected to the connecting section 101a of the housing 101 by screws 104 that are secured in the ground plate 105 having an L-shaped configuration, the metal shield and the ground plate are located at opposite sides of the connecting section 101a. On the other hand, the ground plate 105 presses the mounting section 101b of the housing 101 down thereby securing the housing on the circuit board 108 by means of mounting screws 106 and nuts 107. The mounting screws 106 and nuts 107 also effect an electrical connection between the ground plate 105 and a ground circuit 109 on the circuit board 108. As a result, the metal shield 103 is electrically connected to the ground circuit 109 of the circuit board 108 by means of screws 104, the ground plate 105, mounting screws 106 and nuts 107. The metal shield 103 is grounded by means of mounting screws 106 that perform functions as mounting and grounding of the connector, thereby providing for a relatively simple construction.
The shielded connector 200 shown in FIGS. 5A and 5B is an improved modification of the connector 100 depicted in FIG. 4. Metal shield 203 of shielded connector 200 has connecting tabs 203a at each end and each ground contact 205 has a bifurcated contact section 205a for the insertion of the connecting tabs 203a thereon. The connecting tabs 203a and the bifurcated contact sections 205a are joined together in the opening 201c provided in the housing 201. The ground contact 205 and the housing 201 are secured on a circuit board by means of mounting screws 106 and nuts 107 similar to the arrangement shown in FIG. 4, thus forming an electrical connection of the metal shield 203 through the connecting tabs 203a, the ground contact 205, the mounting screws 106 and nuts 107 to a ground circuit of the circuit board.
However, in order to connect the metal shield 103 of the shielded connector 100 shown in FIG. 4 to the ground circuit 109 of the circuit board 108, in addition to the mounting screws 106, it is necessary to use screws 104, the ground plate 105 and nuts 107. Therefore, the grounding of the metal shield requires a large number of parts; and, since the connection has a number of intermediate points, the reliability of the ground connection of the metal shield 103 is low.
On the other hand, the shielded connector 200 shown in FIGS. 5A and 5B has an advantage compared to the shielded connector 100 shown in FIG. 4 whereon the metal shield 203 has connecting tabs 203a and the ground contact 205 has bifurcated contact sections 205a that are joined in the opening 201c provided in the housing 201, thus making it possible to eliminate the screws 104 for the connection of the metal shield 203 to the ground circuit. Nevertheless, in order to implement the grounding of the metal shield 203 to the circuit board of shielded connector 200, it is still necessary to use a large number of parts, including the mounting screws 106, the ground contact 205 and the nuts 107 without improving the reliability of the ground connection of the shell 203.
Another problem associated with the shielded connectors 100 and 200 shown in FIGS. 4, 5A and 5B consists in the fact that the ground connection of the metal shields 103, 203 requires the installation of the ground plate 105 and the ground contact 205 and the mounting screws 106, 106 on both sides of the metal shields 103, 203, which entails a complicated assembly process.